How do you describe what can’t be seen? Well, thank goodness for the marvelous metaphor. If you took all the metaphors I’ve used over the years and stacked them up end to end, they would reach from Earth to the far side of Uranus and back. But all the good metaphors I’ve used could dance on the head of pin, their substance a thousand times thinner than the width of a human hair. | Which takes me back to nanotechnology. It’s suffering from a chronic case of misleading metaphor. —Howard Lovy
—Merkle and the case of the misleading metaphor  (Howard Lovy’s Nanobot)